On 7/21/25 6:01 AM, Matt Fleming wrote:
On Sat, Jul 19, 2025 at 2:15 PM Jesper Dangaard Brouer hawk@kernel.org wrote:
On 18/07/2025 17.05, Matt Fleming wrote:
[...] diff --git a/tools/testing/selftests/bpf/progs/lpm_trie_bench.c b/tools/testing/selftests/bpf/progs/lpm_trie_bench.c new file mode 100644 index 000000000000..c335718cc240 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/lpm_trie_bench.c @@ -0,0 +1,175 @@
[...]
+static __always_inline void atomic_inc(long *cnt) +{
__atomic_add_fetch(cnt, 1, __ATOMIC_SEQ_CST);+}
+static __always_inline long atomic_swap(long *cnt, long val) +{
return __atomic_exchange_n(cnt, val, __ATOMIC_SEQ_CST);+}
For userspace includes we have similar defines in bench.h. Except they use __ATOMIC_RELAXED and here __ATOMIC_SEQ_CST. Which is the correct to use?
For BPF kernel-side do selftests have another header file that define these `atomic_inc` and `atomic_swap` ?
Actually, we can side step this problem completely by consistently using __sync_fetch_and_add() for duration_ns and hits and removing the atomic operations for DELETE, which doesn't need atomicity anyway since only a single producer can run.
__sync_fetch_and_add() and __atomic_add_fetch() have the same semantics. So indeed tt would be good to just use one of them.
I'll send a v2.